JPH0729241B2 - Hydraulic rotary actuator - Google Patents

Abstract

The annular transmission block (13) is pressed against the transmission face (8) of the cylinder (5) when the oil pressure arrives via the duct (17). At that moment, one of the two grooves (19 or 10) can supply one of the two ducts (9 or 10) in such a way that the oil pressure is transmitted across the fluid-retaining devices (11and 12) to one of the two ends of the chamber (4). The pressure-maintaining device (25) is then charged by stressing its spring (27) and the piston (6) moves into the chamber (4) of the cylinder, carrying along the clamp chuck (7).

Description

Detailed Description of the Invention [Industrial applications]

 The present invention relates to hydraulic rotary reactors.

[Prior art]

In the automatic control of modern machine tools, for example, an operating means for surely opening and closing a collet for rotating a workpiece or a bar-shaped raw material forming the workpiece is required, and this operating means is more than that known in the prior art. It must be adaptable and reliable. Further, this tightening means must be capable of generating a large torque at high speed rotation. It is known in the art to use hydraulic control devices. However, it is also well known that the design must properly solve various problems that occur when transmitting the pressure of the control fluid from the fixed part to the rotating part of the hydraulic circuit. Conventionally used rotary seals operate at a high speed and transmit high pressure, and easily generate heat beyond an allowable range, which is not preferable for the reliability and durability of machine tools. For this reason, for example, in the specification of French Patent No. 2180425, an annular groove is provided in the hole of the fixed portion for transmitting pressure from the inlet connection portion, and a hole facing the groove is provided in the rotating portion. It has been proposed to transmit hydraulic pressure through a line normally closed by a ball valve to a chamber communicating with the cylinder of the actuator. In pressure transmission, it is necessary to provide a gap between the rotating part and the fixed part, which functions as a labyrinth packing and causes a large pressure drop. This and other similar configurations, such as the one described in U.S. Pat. No. 3,933,061 and including a pressure distribution device for continuously transmitting pressure in the rotary seal, causes the disadvantages described above.

[Problems to be Solved by the Invention]

The present invention aims at proposing a new solution to this problem.

[Means for Solving the Problems]

In order to achieve such an object, a hydraulic control circuit having a piston integral with a tightening chuck, a control cylinder integral with a main shaft, a stationary portion supported by a frame, and a rotating portion supported by the main spindle is provided. The above object is achieved by providing a hydraulic rotary actuator for controlling the tightening or releasing of the collet or mandrel of the machine tool. In this hydraulic rotary actuator, the rotary portion of the control circuit has means for holding the control fluid and means for maintaining the fluid under pressure, and temporarily controls the stationary portion and the rotary portion of the hydraulic circuit only for control operation. Electrically connecting means are provided between the stationary part and the rotating part.

【Example】

The device shown in the drawing is associated with the rotating part of the hydraulic control circuit and is provided with means for maintaining the pressure of the cylinder constant once a command has been given, so that, as in the prior art device, a water seal is provided. The continuous transmission of pressure is no longer necessary. This performance is described below.
It is caused by the pressure on the transfer block. FIG. 1 schematically shows the principle of this device. In the figure, the frame 1 is, for example, a headstock of a lathe. In this headstock, a main shaft body 3 rotated by a device (not shown) is supported by a bearing 2. A chamber 4 is provided in a front portion of the main shaft body 3, and a wall of the chamber 4 forms a control cylinder 5, in which a piston 6 integrated with a tightening chuck is slid. The tightening chuck 7 is connected to a collet (not shown) by a known means, and when the tightening chuck 7 is displaced in the axial direction between the forward position and the retracted position, the workpiece or the rod is opened or held, or If the device is used for controlling a tool, it will open and / or close the collet while holding the tool, even in the rotating state. The control cylinder 5 is provided on its left side with an annular and flat transmission surface 8 in the lines 9 and 10 which are formed inside the control cylinder 5 and extend and end on each of two sides of the piston 6. The communicating orifice is open to the transmission surface 8. Holding means 11 and 12 as control fluid holding means are arranged in the control cylinder 5 along the lines 9 and 10. These retaining means 11 and 12 are represented by simple ball valves in FIG. 1, but as will be seen below, these devices move immediately upon command, opening the depressurizing line and While continuing to open them, the pressurizing pipeline is provided so as to open as much as the oil can pass without loss of pressure. Furthermore, these two holding means 11 and 12 have the opposite functions of either pressurizing or depressurizing, depending on the direction of movement of the piston 6 to be controlled. A transmission block 13 which is located between the frame 1 and the main shaft body 3 and which is coaxial with the main shaft body 3 and includes an annular piece is provided. This annular piece is provided with a flange 14 acting as a piston, which is biased by a spring 15 and into a recess 16 through which oil under pressure can be supplied by a line 17 across the frame 1. It is housed. This transmission block 13 is provided with a flat annular surface 18 facing the transmission surface 8 and in this annular surface 18 two annular grooves 19 are provided.
And 20 are formed. The radius of each of these annular grooves 19 and 20 corresponds to the distance between the axis of rotation of the device and the opening of the lines 9 and 10 on the transmission surface 8. The transmission surface 8 is a rotating surface, while the annular surface 18 is a stationary surface. Normally, the transmission block 13 is separated from the transmission surface 8 by the spring 15. However, when a command to move the tightening chuck 7 is issued,
The annular surface 18 is pressed against the transmission surface 8 by the hydraulic pressure applied to the back side of the flange 14. Therefore, the annular groove 19 communicating with the two control lines 21 and 22.
Compressed oil is supplied to either or
The other communicates with the depressurizing pipe. These operations are controlled by the valve 23. By means of the valve 23 the control lines 21 and 22 are used oppositely as pressurizing and depressurizing lines, while the line 24 connected to the device by the valve 24 carries compressed oil with each movement. . Therefore, friction occurs between the annular surface 18 and the transmission surface 8 only during control operations. However, inside the control cylinder 5, pressure maintaining means for maintaining the chamber 4 in a pressurized state is provided. In FIG. 1, these devices are represented by a cylindrical chamber 25 in which a free piston 26 under the force of a spring 27 slides. The end of the cylindrical chamber 25 facing the spring 27 communicates with the end of the chamber 4 in which the oil compressed by the pipe 28 and the ball valve 29 is put. Therefore, the oil entering the chamber 4 moves the piston 6 on the one hand and, on the other hand, pushes back the free piston 26 in the cylindrical chamber 25 against the action of the spring 27. On the contrary, when the left chamber of the chamber 4 is pressurized, the free piston 26 moves and the cylindrical chamber 25 enters a hydraulic state, and the free piston 26 is pushed back against the action of the spring 27. Therefore, the chamber 4 is kept under pressure by this pressure maintaining means except during the so-called control when the annular surface 18 of the transmission block 13 and the control cylinder 5 are separated. Since the volume of oil sent by this method matches the force applied to the spring 27, the spring 27 keeps the piston 6 pressurized after this even if oil leakage occurs during operation of this device. Regarding this point, since the amount of oil entering the chamber 4 and the cylindrical chamber 25 exerts a necessary pressure on the spring 27,
The amount of oil leakage is automatically compensated for each control movement. Since it can maintain the pressure as described above, it is also used as a pressure accumulator. 2 and 3 show in detail one embodiment of the invention whose principle is shown in FIG. FIG. 2 shows a control cylinder 5 in which a frame 1, a bearing 2, a main shaft body 3 composed of a plurality of members, a chamber 4 and a piston 6 which is integral with a tightening chuck 7 slides.
And a portion of the main shaft body that constitutes the. A threaded portion 30 can be seen on the front of the tightening chuck 7. The threaded portion 30 allows a pull bar to be attached to the chuck that can actuate the tightening cone portion of the chuck. In FIG. 2, an annular surface 18, which is the stationary transmission surface of the transmission block 13, has moved towards the transmission surface 8 of the control cylinder 5. The flange 14 of the transmission block 13 is engaged in a case in which compressed oil can be supplied through the inlet connection 31, to which the conduit indicated by 17 in FIG. 1 is connected. . The action of the spring 15 shown in FIG. 1 is in this case moved in the bush 33 and is acted on by a screw 32 biased by the spring 34, by means of which the transmission block 13 is normally separated from the control cylinder 5. It is placed. Grooves 35 and 36 are provided on the outer cylindrical surface of the transmission block 13. These grooves 35 and 36 are connected to control lines 21 and 22 which are formed on the frame 1 and are pressurizing or depressurizing pipes on the outer periphery of the frame 1 when the transmission block 13 is in the operating position (not shown). ) Communicated. The connections to the control lines 21 and 22 which are the pressurizing or depressurizing pipes are indicated by 37 and 38 in FIG. With respect to the annular grooves 19 and 20 formed in the annular surface 18, these grooves are connected to the grooves 35 and 36 through the respective holes 39, and the connections 37 and 38 communicate with the control lines 21 and 22. To be done. Regarding the pressure maintaining means for maintaining the pressure under pressure, it is indicated by the cylindrical chamber 25, the housing 42, etc. in the embodiment shown in FIG. Further, a retaining ring 40 is arranged in this pressure maintaining means. The retaining ring 40 is fixed with a series of rods that engage several housings 42 of the control cylinder 5, into which springs 43 are inserted. Therefore, the retaining ring 40 is constantly pressed by the spring 43 against the annular front surface of the control cylinder 5. The other annular front side surface of the control cylinder 5 has a first
Cylindrical chamber 25 corresponding to the cylindrical chamber 25 of the embodiment shown in the figure
There are some openings. Therefore, the cylindrical chamber 25 and the housing 42 shown in FIG. 2 are arranged on the outer periphery of the control cylinder 5. In each of the cylindrical chambers 25 are inserted two free pistons 44 and 45 which act as the ball valve device 29 in FIG. Specifically, the space between the two free pistons 44 and 45 communicates with the rear end of the chamber 4 through the hole 46, and the space between the free piston 45 and the bottom of the cylindrical chamber 25 through the hole 47. It communicates with the other end of the chamber 4. Therefore, if hydraulic pressure is applied to the rear end of the chamber 4, this hydraulic pressure will increase to 2
It is transmitted to the cylindrical chamber 25 between the two free pistons 44 and 45, so that only the free piston 44 resists the spring 43 and is pushed back to the left. Also, due to the hydraulic pressure applied to the rear end of the chamber 4 by the piston 6,
Between the free piston 44 and the free piston 45, the right side, that is, the threaded portion 30 of the tightening chuck 7 moves toward the inner wall of the chamber 4 of the control cylinder 5 located in such a direction as to project from the control cylinder 5. The cylindrical chamber 25 is expanded. At this time, the free piston 45 acts on the pipe line 47 as a closing valve body. Therefore, as the piston 6 moves, the compressed oil in the other end, that is, the right end of the chamber 4 is connected to the other end, that is, the right end of the chamber 4, which will be described later, although not shown in FIG. The depressurizing pipes are brought into the depressurized state through the respective one of the holding members 11 and 12. In this case, the retaining ring 40 can be moved a considerable distance rearward, so that even if there is an oil leak during operation of the device, the volume of oil that can enter between the two free pistons 44 and 45. Leakage can be supplemented without reducing the pressure in the chamber 4. When there is a command to move the piston 6 from the right to the left, the hydraulic pressure is applied to the right end of the chamber 4 through the one conduit 56 of each of the holding means 11 and 12 in reverse. Oil pressure is applied to the front end of the. This causes the two free pistons 44 and 45 to be pushed to the left against the action of the spring 43. During this time, the left side portion of the chamber 4 is connected to the depressurizing pipeline through the other pipelines 56 of the holding means 11 and 12, respectively, so that a desired operation can be obtained. In the two parallel holes formed inside the control cylinder 5, there are two fluid holding means 11 which are control fluid holding means.
12 is installed. Each of these devices is fitted on one side with the conduits 48 and 49 into the annular grooves 19 and 20 of the transmission block 13 and on the other side with the conduit 56.
Communicate with both ends of the chamber 4. The holding means 11 is shown in FIG. That is, a valve piston 51 having two rods 52 slides on a cylinder 50 at the center of the holding means. Cylinder 50 has conduit 48 on one side of valve piston 51.
On the other side is connected to line 49. Both ends of the cylinder 50 are restricted by respective seats 53, and the balls 54 urged by springs 55 are pressed against the seats 53. These sheets 53 are accommodated in the widened portion of the lateral hole that accommodates the holding means. As shown, each of the seats 53 causes one of the two conduits 48 and 49 and one of the two conduits 56 toward both ends of the cylinder 50 in which the ball 54 is located to be positioned by the cylinder 50. Communicated. Further, although not shown, the two conduits 56 extending toward both ends of the cylinder 50 are connected to and communicate with one of the two ends of the chamber 4 of the control cylinder 5, respectively. The operation of this holding means is as follows. For example, when hydraulic pressure is applied from the valve 23 to the connection 38, the conduit of the control cylinder 5 passes through the groove 36 of the transmission block 13.
48 is pressurized. In this case, the valve piston 51 of the holding means 11 is displaced rightward. Along with this, the ball 54 disposed in the cylinder 50 in which the conduit 48 is bored is such that the rod 52 separates from the ball 54 due to the displacement of the valve piston 51 to the right.
55 is pushed toward the seat 53. However, if the hydraulic pressure in the cylinder 50 increases, the hydraulic pressure will
As a result, the ball 54 is pushed to the left against the action of the spring 55. Therefore, a gap is created between the seat 53 and the ball 54, and as a result, the cylinder 50 allows the conduit 48 and the conduit 56 to communicate with each other.
Hydraulic pressure is applied to 56. On the other hand, another ball 54 located in the direction of the other end of the cylinder 50 also separates from the seat 53, which is due to the action of the rod 52. With such an operating state, the conduit 56 on the left side of the holding means 11 is
The hydraulic oil is supplied to the pipe 48 from the line 48, and the compressed oil is supplied while the pressure continues. The conduit 56 communicates with one end of the chamber 4 of the control cylinder 5. On the other hand, since the pipe line 56 arranged at the other end of the holding means 11 communicates with the other end portion of the chamber 4 of the control cylinder 5, the ball 54 of the pipe 54 extends from the seat 53 to the rod 52 of the valve piston 51.
While being separated from each other, the chamber 4 is continuously connected as a depressurizing line and is connected to the depressurizing line by a line 49. If hydraulic pressure passes through the line 49 and reaches the inside of the cylinder 50, the lines 48, 49, 56 and 56 have opposite functions,
The piston is moved in the opposite direction. Also, when hydraulic pressure is not applied to the pipelines 48, 49, the balls 54, 54 at both ends of the cylinder 50 are urged to the seat 53 by the springs 55, 55, respectively, and the communication with the pipelines 48, 49 is cut off. It Therefore, the balls 54, 54 act as a closing valve body. As described above, the chamber 4 of the control cylinder 5 is kept under pressure in cooperation with the actions of the cylindrical chamber 25 and the housing 42. The two holding means 11 and the holding means 12 have the same configuration and are operated in parallel, and the reliability and safety of the operation can be improved by providing the two present devices. The commands for the movement of the machine elements described above are provided by electrical circuits which are connected to a control system usually employed on machine tools. Therefore, the valve 23 that distributes the hydraulic pressure to one of the control pipes 21 and 22 and puts the other into a depressurized state is operated by a preset program. Further, the position detectors 57 and 58 detect the holding ring 40 and the holding ring arranged at one end of the tightening chuck 7, respectively. These detectors stop the supply of compressed oil when the mechanical element in question is in its final position. A device that is reliable, compact and very efficient in hydraulic operation is achieved in this way. In this device, fixed part (frame 1, transmission block 13) and rotating part (spindle 3, control cylinder 5)
Since the pressure is transmitted by and only during the control operation, it is possible to control the tightening chuck 7 of the main body rotating at a high speed. Therefore, hydraulic pressure can be transmitted even when the rotating portion (main shaft 3, control cylinder 5) is rotating, and when used in an automatic machine or the like, it is possible to feed the work material without stopping the collet. . Further, during the control operation, the transmission block 13 of the fixed portion (frame 1, transmission block 13) and the control cylinder 5 of the rotating portion (spindle 3, control cylinder 5) come into close contact with each other, so that even if hydraulic pressure is applied. The risk of leakage is extremely low. Next, the internal space of the main shaft body 3 containing the compressed oil is communicated with the pressure maintaining means operated under the influence of the spring 43. Therefore, the internal space of the main shaft body 3 can always be maintained in a pressure state, and the influence of oil leakage is eliminated. In this way, it is possible to prevent both oil loss due to the leaky rotary seal and heat generation when the seal is tight, which cannot be avoided in the past. This controller is a single device that is completed by itself,
It can be mounted as an auxiliary means on the headstock of the lathe, for example at its rear. Alternatively, it may be integrally attached to the headstock.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the operating principle of the device of the present invention and its main constituent elements.

FIG. 2 is a sectional view showing an embodiment of the device in detail.

FIG. 3 is an enlarged partial cross-sectional view taken along the line III-III in FIG. 2 showing one of the fluid holding means attached to the main shaft.

[Explanation of symbols]

1 ... Frame, 3 ... Spindle body, 4 ... Chamber, 5 ... Control cylinder, 6 ... Piston, 7 ... Tightening chuck, 8 ... Transmission surface, 9,10 ... Pipe line, 11, 12 ... Holding means, 13 ... Transmission block, 18 ... Annular surface, 19, 20 ......
Annular groove, 21,22 ... Control line, 23,24 ... Valve, 25 ...
… Cylindrical chamber, 26,44,45 …… Free piston, 27,34,43 ……
Spring, 32 …… Screw, 35,36 …… Groove, 37,38 …… Connecting part, 39 …… Hole, 40 …… Holding ring, 42 …… Housing,
48 and 49, 56 ...... pipe, 51 ...... valve piston, 54 ...... balls, 57 and 58 ...... position sensor.

Claims (9)

[Claims] 1. A hydraulic rotary actuator for controlling tightening of a collet or a mandrel of a machine tool, wherein the hydraulic rotary actuator includes a piston integrated with a tightening chuck, a control cylinder integrated with a main shaft body, A hydraulic control circuit including a stationary portion supported by the frame, a rotating portion supported by the main shaft, and a transmission means is provided, and the rotating portion of the control circuit applies the control fluid holding means and the control fluid. Pressure maintaining means for maintaining pressure, between the stationary part and the rotating part of the hydraulic control circuit, the stationary part and the rotating part while the rotating part supported by the main shaft body performs control operation while rotating. A hydraulic rotary actuator, characterized in that said transmission means for temporarily connecting the parts are arranged. 2. The actuator according to claim 1, wherein the transmission means includes an operating position in which opposing transmission surfaces and annular surfaces of the main shaft body and the transmission block are pressed against each other, and the two transmission positions. A transmission block which can be moved to or from a non-operating position where the surfaces are separated, and the transmission block is provided with an internal conduit connected to an external opening arranged on an annular surface of the transmission block. An actuator characterized by being provided. 3. The actuator according to claim 2, wherein the outer opening is formed by an annular groove arranged over the entire annular surface of the transmission block, and the external opening is formed in the main shaft body of the hydraulic control circuit. There is a control conduit opening in the transmission surface of the supported rotating part and facing the groove, said conduit being connected to each end of the chamber of the control cylinder, and being connected to each of said conduits. An actuator characterized in that a control fluid holding means is provided. 4. The actuator according to claim 3, wherein each of the control fluid holding means includes two spring-biased closing valve bodies arranged to face each other in a cylinder of the holding means. And a cylinder provided in the holding means in which a valve piston having two opposed rods slides to form a control fluid holding means, and when one closed valve body is in an open position, the other closed An actuator characterized in that the valve piston and the closing valve body are maintained so that the valve body always comes to an open position. 5. The actuator according to claim 1, wherein each of the pressure maintaining means for maintaining the control fluid in a pressurized state functions as a pressure accumulator, and a cylindrical chamber, A free piston sliding in the cylindrical chamber, a housing, a series of springs arranged in the housing acting parallel to the axis of the housing, and a retaining ring biased by the spring and the free piston. Have
When the cylindrical chamber is pressurized, this fluid pressure acts on the free piston and the retaining ring moves so as to apply stress to the spring, so that oil leakage occurs in the cylindrical chamber and the housing. An actuator characterized by preventing pressure drop. 6. An actuator according to claim 5, characterized in that the stroke of the retaining ring is detected by a position detector which automatically controls the start of the supply of control fluid of the actuator. 7. The actuator according to claim 2, wherein the transmission block is urged by an elastic element that separates the transmission block from a transmission surface of the rotating portion of the control circuit, and the hydraulic control means controls the rotating portion. The actuator according to claim 2, wherein the actuator acts to press the transmission block against the transmission surface during operation. 8. The actuator according to claim 7, wherein the transmission block is an annular member coaxial with the axis of the main shaft body, and the annular surface of the transmission block is flat. The displacement of the actuator is parallel to the axis of the main shaft body. 9. The actuator according to claim 1, wherein the pressure maintaining means for maintaining the control fluid in a pressurized state is mounted in the control cylinder.